Around 1:45 p.m. airline screeners used a wand device to sweep certain passengers before boarding a plane to Dallas and discovered an unloaded weapon, a Transportation Security Administration spokesman said.

Whitney Brewer, a Southwest Airlines spokeswoman, said a gun was found in carry-on luggage as a man was going through a security checkpoint.

"Once the police department was notified of the breach, all screening stopped," Airport Manager Richard McCollum said. "In about three minutes the decision was made to empty the concourse."

About 350 passengers had to leave the area and go through the baggage and metal detectors again. Officials delayed one American Eagle and two Southwest planes from departing, McCollum said.

As many as 500 people were affected, either missing connections in other cities or waiting longer at the Amarillo airport to get past security, he said.

Airport police, FBI and Federal Aviation Administration personnel detained the man and questioned him for about two hours. The man answered questions and filled out paperwork for a criminal background check, McCollum said.

"He's not being arrested," McCollum said later in the afternoon. "He's basically free to go."

The man still can receive a fine from $500 to $10,000.

Manny Menard of San Antonio was getting ready to board the Southwest plane when the ordeal began.

"We were told to stop and take our seats in the lobby," Menard said, who was on his way to Dallas. "The flight attendants wouldn't tell us anything, but we heard that there was a firearm in a bag."

When Menard went through the baggage screening area the first time, he said he remembered thinking how thoroughly the screeners searched everyone. He had to remove his belt and officials searched his bags by hand.

"I travel a lot, and I thought it was really secure here," he said. "I guess they weren't checking the right people."

Melinda Dergregorian and her two sons waited Thursday afternoon to pick up her husband.

"It was just a terrifying feeling," she said when she first walked into the airport. "I didn't know what was going on, and I thought something terrible happened."

Al Dergregorian, whose flight arrived on time, said he knew something was wrong when the security checkpoint line stretched unusually long.

"They didn't tell us anything on the plane," he said. "Something like this was bound to happen."

Ken Ledbetter of Atlanta waited in the airport restaurant, drinking a beer before his flight on Delta Airlines. People at the car rental return told him of the security breach and the delay.

"I got here early to see if I could get an earlier flight," he said.

Ledbetter said hearing about guns in the airport does not make him leery of flying.

"You gotta do it," he said. "Flying is still safer than driving."

Ted Hennis of Amarillo said he waited about 40 minutes in the line to get up to the security screeners. He was taking off his belt and checking for loose change as he approached the security personnel.

"All we heard was someone got through with a gun," he said. "I'm glad they found him."

McConnell praised the airport personnel for acting quickly.

"All employees did their jobs," he said. "It just inconvenienced everyone involved."